Three stage load compensating brake



March 5, 1957 N. SUDDUTH 2,784,039

THREE STAGE LOAD COMPENSATING BRAKE Filed June 13, 1955 2 Sheets-Sheet lINVENTOR Henry Norcon Sudduch ATTORNEYS March 5, 1957 H. N. SUDDUTH2,784,039

THREE STAGE LOAD COMPENSATIINIG" BRAKE Filed June 13, 1955 2Sheets-Sheet 2 LOkO RFD- Fis. Z

INVENTOR Henry NOrcon Sudduch BY 00 L 32 4 ATTORNEYS THREE STAGE LOADCOMPENSATING BRAKE Henry Norton Sudduth, Watertown, N. Y., assignor toThe New York Air Brake Company, a corporation of New Jersey ApplicationJune 13, 1955, Serial No. 515,135

4 Claims. (Cl. 303-22) This invention relates to multiple position,empty-andload valves for use with automatic air brakes, particularlyfreight car brakes.

Two-position empty-and-load brakes have long been in use on type offreight cars that carry bulk loads and are almost invariably empty orfully loaded. The respond to the relative positions assumed undervarying load by two parts of a truck suspension, commonly the truckframe, and the spring-mounted truck bolster.

Steadily increasing operating speeds and greater disparity between emptyand loaded weights of the type of freight car susceptible to highlyvariable loading have created a condition requiring adjustment ofbraking force in relation to load (load compensation) betterthan can beattained by any two-position empty-and-load brake.

An application of Ross and Safiord, Serial-Number 444,896, filed July21, 1954, issued January 3, 1956, as Patent 2,729,515, discloses athree-position valve i. 'e., one which establishes braking forces atthree basic levels using a 12 inch plain cylinder. The selector valveuses principles of proven practicality.

One of the important features was the use of two'proportioning valves,one for empty and the otherjfor intermediate load conditions, withmeansto afford an independent exhaust path around the proportionirig valves.

The present invention relates to this exhaust'path and provides betterreleasing action in both empty and intermediate settings and also whenthe retainer is'set. The compensating volumes characteristic of theSafford and Ross invention are used, and so also is the imp'rovedproportioning valve.

The invention will now be described byreference-to the accompanyingdrawings which 'show the AB valveand reservoirs on a smailer scale thanthe related load mechanism, the latter being shown in vertical'section'and diagrammatically to the extent that the ports are shown as if theylay all in the plane of section.

Fig. 1 shows the AB valve, itsreservoir, brake-pipe and connections inelevation and the selectorvalve mechanism-with its connections in axialsection.

Fig. 2 shows the brake cylinder in fragmentary elevation, a portion of atruck frame in elevation in broken lines, and in vertical section, theweighing valve,:cut-off valve, two proportioning valves, thecompensating volume, and appropriate pipes and passages.

Figs. 1 and 2 when assembled, one above the other, afford a diagram ofthe essential brake equipment for one-car.

All statements of direction refer to parts as positioned in Figs. 1-2.

It is contemplated that the invention'will beu'sed-with the AB brake andit is iilustrated'as so used. The AB brake is in current use and, in thepresent disclosure, typifies any valve involving the triple'valveprinciple in conjunction with the displacement type of automatic airbrake.

The pipe bracket 6 carries the. service portion 7 and the emergencyportion 8. The brake pipe 9 is connected to amass Patented Mar. 5, 1957the bracket 6 through a branch pipe in which is inserted a standard dustcollector and cut-out cock 11. The emergency reservoir 12 and auxiliaryreservoir 13 are connected by pipes to the bracket 6. Pipe 14 is thebrake cylinder connection which in conventional AB installations leadsdirectly to the brake cylinder, but .here leads through theempty-and-load mechanism of the present invention. The connection 9A isin free communication with the brake pipe a. A conventionalfour-position retainer 20 is shown at the end of the usual retainerpipe.

To simplify description and avoid multiplying reference numerals, asingle numeral will be used to designate any continuous passage and anypipe in free communication with such a passage. Since the commercialembodiment will difier somewhat in arrangement from the diagrammaticshowing, the sectional construction of the housings (though indicatedschematically in the drawings) will not be elaborated in thedescription. Accepted commercial practices will, of course, be used, andnothing deemed patentable is involved.

The brake cylinder connection leads to chamber 15A which is in one waycommunication with chamber 15B past a lightly loaded check valve 15C.This check valve permits practically free flow from 15A to 15B andprevents flow in the reverse direction. Chamber 15B is in effect asingle space, being two valve chambers which freely communicate.

There are three selectively opened poppet valves, namely a load valve 16which when held open allows flow from chamber 15A, also an empty valve17 and an intermediate valve 18 each controlling a flow from 15B. Eachof these three valves is urged toward its seat by pressure in therelated chamber 15A or 15B, and by respective ones of the three lightcoil compression springs 19. Since valve 16 controls exhaust flow, itsspring 19 should be very light.

Cylinder 22 is equipped with any usual slack adjuster, diagrammaticallyindicated at 23.

The valves 16, 17 and 18 are identical, and each is forced open by oneof three identical tappets 24. These are sealed against leakage both intheir valve-open and valve-closed positions by one or the other of thegaskets 25, 26 which encircle each of them and which are identified bythese numbers on the tappet for valve 16.

The valves 16, 17, 13 are held open selectively by the annular lobe 27in rod 28 which rod connects reset piston 29 with the largerload-setting piston 31. Piston 29 is called the reset piston, because inthe first phase of every load-weighing operation piston 29 is forced allthe way to the right until empty position (shown in Fig. 1) is reached.After this the weighing operation proceeds, as will later be described.

Reset piston 29 works in a cylinder 32 closed at its left-hand end andload setting piston 31 works in a cylinder 33 of larger diameter thancylinder 32. A stop ring 34 is clamped between the main housing and anextension thereof. The latter encloses a coaxial cylinder 35, which isclosed at its right-hand end and conveniently is of the same diameter ascylinder 33. Ring 34 limits the leftward motion of piston 37. The spacebetween pistons 29 and 31 is vented to atmosphere.

The right-hand end of rod 28 has a counterbore'to receive the end of rod36 attached to the intermediate setting piston 37 which works incylinder 35. Rod '36 is dimensioned to limit the approach of pistons 31and 37 to one another. On opposite sides of lobe 27 are annular grooves38, 39 which are engaged by the nose 41 on the stem oflatch-piston 42. Athird groove 40 is located on stem 28 further to the right. Piston 42 isbiased downward to latch-engagingposition by spring 43.

Piston 42 works in a cylinder as shown. The space above the piston isvented to atmosphere and the space below the piston is in freecommunication with passage 44. The cylinder space 32 to the left ofreset piston 29 communicates with passage 44 through a choke 45.

The parts are proportioned as will now be described. In empty position(shown in Fig. l) pistons 31 and 37 are to the right as far as they go,and nose 41 engages in groove 38. This position is reached by admittingpressure fluid to cylinder 32 to the left of piston 29. The pressurefluid arrives from the brake pipe via passage 44 and choke 45, so latchpiston 42 will first be lifted. In intermediate position lobe 27depresses the tappet for valve 18 and latch nose 41 is in groove 39.This position is reached by admitting pressure fiuid via passage 46 tothe right side of piston 37 which is arrested by stop ring 34 with theparts positioned as stated.

In load position lobe 27 depresses the tappet for valve 16 and latchnose 41 is in groove 49. This position is reached by admitting pressurefluid to both passages 46 and 47 so that both pistons 31 and 37 areurged to the left, and piston 31 moves to the left to its limit ofmotion. 1

As will later appear more clearly, passages 46 and 47 are each fed frompassage 44 through a choke 48, passage 4? and the weighing cylinder.Hence, latch nose 41 is retracted before the shift to eitherintermediate or load position commences.

The valves 16, 17 and 18 control flows from line 14 toward the brakecylinder. They open selectively as to such flows. When valve 16 is openthe flow is free in both directions.

When valve 17 is open the flow is one-way (because of valve 15C) viapassage 51 (which is in free communication with compensating volume 52)and then through the proportioning valve 53 to brake cylinder passage21. Valve 53 is set to aiford a proportionally reduced brake cylinderpressure appropriate to an empty car.

When valve 18 is open, the flow is via passage 54 which communicatesthrough check valve 55 with compensating volume 52. Passage 54communicates with brake cylinder passage 21 through a proportioningvalve 56, set to proportion an intermediate brake cylinder pressure.

Respective proportioning valves close when pressures in their dischargesides rise to a characteristic fraction of the pressure on their supplysides. For each valve the characteristic fraction is determined by therelative proportions of two diaphragms which form a differentialpressure motor. Though each proportioning valve discharges to passage21, neither can interfere when valve 16 is open; nor can they interferewith one another because they are set for different fractionalreductions. When valve 17 is open, check valve 55 isolates passage 54from compensating volume 52. When valve 18 is open, valve 53 would closewhile 56 was still open and so would not interfere with the controleifected when 56 closed.

With a 12 inch plain brake cylinder limited to inch travel, fullequalization with standard reservoir volumes would be reached at 50 p.s. i. in pipe 14 in all three settings of the selector valve if volume52 were 365 cu. in. and connected in light position and if it were 300cu. in. and connected in intermediate position. A single volume between300 and 365 cu. in. (325 cu. in. has been used successfully) gives aclose enough approximation to full equalization at 50 p. s. i. for allpractical purposes, and is shown in Fig. 2.

The proportioning valves 53 and 56 are functionally similar.Mechanically they differ only in that the difier entials betweendiaphragm areas are so chosen that the valves 53 and 56 aiford dilferentproportional pressure reductions.

Only valve 53 is shown in section and a description of it will suifice.

The flow-controlling valve is a poppet valve 58 which opens in thedirection of flow from passage 51 through valve-seat 59 tobrake-cylinder passage 21. There is no reverse flow. The valve 58 ismoved in the closing direction by force developed through a coilcompression spring 61 confined between a spring seat 62, which is inthrust relation to valve 58, and a spring-seat 63 which is sustained byadiustable thrust screw 64. The screw 64 is mounted in the hub 65 whichconnects the centers of two diaphragms 66, 67 of unequal areas whoseperipheries are clamped in the housing of the valve structure.

The upper and smaller diaphragm 66 is exposed to atmospheric pressure onits upper face, whereas the lower diaphragm 67 is similarly exposed onits lower face. The space 68 between the diaphragms is exposed topressure in brake cylinder connection 21, but the connection which soexposes it is preferably not a free one. Instead, a valve 69 loaded byspring 71 is used to produce a pressure drop such that pressure inpassage 21 must reach about 9 p. s. i. before proportioning starts. Thisis to ensure that the brake piston will start to move beforeproportioning starts. To permit back flow from chamber 68 a reverselyset check valve 72, lightly loaded by spring 73, controlsv a bleed port,which conveniently can lead through valve 69.

The spring 61 atfords a thrust connection between hub 65 and valve 58.It is convenient but not strictly necessary that this connection beelastic.

Valve 56 is identical with valve 53 except that the diaphragrnscorresponding to 66 and 67 afford a ditferent area differential. Valve56 controls fiow from passage 54 to passage 21 and produces a smallerproportional reduction, to that brake cylinder pressures limited by itare higher.

Various dilferent load-weighing mechanisms might be used but one (forwhich no novelty is here claimed) is illustrated in the interests ofcompleteness.

A vertical cylinder 75 is mounted on the spring-supported truck bolster(not shown) and contains a piston 76 whose rod 77 can collide at itsupper end with a lug 78 on the truck frame79 unless the piston is in itslowermost position. The upper end of the cylinder is vented toatmosphere at 81, and there are two side-ports with which theconnections 46 and 47 respectively communicate. On an empty car thepiston 76 cannot rise high enough to expose either port, but at halfload it can rise far enough to expose the port leading to passage 46,and on a loaded car it can go further and also expose the port leadingto passage 47.

Recourse is had to the familiar expedient of activating the piston 76 inabout the first 50 p. s. i. of a system charge starting with a ventedbrake pipe, and then causing the piston to lower fully, and remainlowered until brake pipe pressure is once more reduced substantially toatmospheric pressure.

The cycle is controlled by the cut-off valve which is identified by thenumeral 82 applied to its housing (see Fig. 2). This housing iscontinuously connected with the brake pipe by connection 9A and thevalve controls communication between 9A and passage 44 which in turn isconnected through choke 48 and passage 49 with the cylinder 75 at apoint below piston 76. The cut-oif valve proper is a poppet valve 83which closes against its seat 84 in the direction of flow from 9A topassage 44. The valve 83 is biased in a closing direction by a lightspring 85. Enclosed in the valve 83 is a cylinder in which a piston 86(smaller in diameter than the seated area of the valve 83) mayreciprocate. Piston 86 is exposed to the pressures above and below-valve83, at least when the valve is closed, and is connecetd to a stem 87which carrier a collar or encircling flange 88 fixed to it.

A diaphragm 89 is clamped at its periphery between parts of the housing82 and is subject to pressure in passage 44 acting upward upon it. Theupper face of diaphragm 89 is exposed to atmospheric pressure. At

its center diaphragm 89 carries hub 91 biased downward (i. e., in thedirection to open valve 83) byspring 92 which is stronger than spring85. Stem 87 is slidable longitudinally through a guideway in hub 91 andis urged downward by a light spring 93 which reacts between a portion ofhub 91 and the upper end of stem 87, which has an enlarged head.

A tiltable spring seated vent valve 94 has a stem 95 which projects intothe path of flange 88. Tilting of the vent valve cocks it otf its seatand opens it, thus venting connection 44.

Assume the brake pipe 9 has been vented and recharging starts. Brakepipe air will flow through 9A, past valve 83 (which is then held open byspring 92) to passage 44. The chokes 45 and 48 assure that latch piston42 is first forced back, then piston 29 is forced to the right, settingthe valve selector to empty position. At this time or slightly later,piston 76 will start to rise. The distance it can rise until arrested bystop 78 depends on the load on the car, and determines the positionassumed by the selector valve. If neither port 46 or 47 is exposed theselector remains in empty position. If 46 only is exposed, piston 37moves the selector to intermediate position. If 47 is also exposed,piston 31 moves the selector all the way to load position.

When passage 44 has been charged to about 50 p. s. i. diaphragm 89 willhave lifted enough to allow valve 83 to close. This stops the pressurerise in passage 44 but brake pipe pressure continues to rise in 9A. Soonvalve 83 is firmly seated by pressure beneath it and piston 86 issubject to an increasing pressure difierential, acting upward. Beforecharging is complete, piston 86 overpowers spring 93, flange 88 engagesstem 95 and cocks valve 94 ofi its seat.

This vents connection 44, causing latch 41 to re-engage, and seatingvalve 83 so firmly by pressure that it cannot again open until the brakepipe pressure falls below about p. s. i.

The cut-ofi valve above described is not the invention of thisapplicant.

The setting of the valve selector either connects the AB valve directlyto the brake cylinder, or interposes one or the other proportioningvalve with volume 52 connected to draw air from the auxiliary reservoirand compensate for the reduced flows permitted by the proportioningvalves.

In the load position lobe 27 depressed the left-most stem 24 so thatvalve 16 is held open. Valves 17 and 18 remain closed. Hencebrake-cylinder pipe 14 affords free communication in both directionsbetween the AB valve and the brake cylinder. The AB valve functionsnormally.

In the empty position, shown in Figure l, lobe 27 depresses theright-hand stem 24, so that valve 17 is held open. Valves 16 and 18 areclosed by their springs and are urged to their seats when fluid pressureis admitted through pipe 14 to chambers 15A and 15B. Assume that underthe conditions just stated the AB valve admits air to pipe 14. From pipe14 air flows past valve 150 to chamber 15B, past valve 17 and then viapassage 51 to compensating volume 52 and also to seat 59 of the emptyproportioning valve 53. The valve disc 58 will lift and air will flow tothe brake cylinder 22 via passage 21.

Development of pressure in passage 21, after a delay imposed by valve69, will cause development of pressure in chamber 68, and eventually theempty proportioning valve 53 will act to limit brake cylinder pressureto a low value (by closing valve disc 58 against seat 59). Observe thatcheck valve 55 prevents flow from compensating volume 52 toproportioning valve 56.

In intermediate load position lobe 27 holds valve 13 open. The flow frompipe 14 is through check valve 15C to chamber 15B, past valve 18 (valves16 and 17 being closed) 'and then via :passage 54 to intermediate.proportioning valve 56, and past check valve 55 .to compensating volume52. Volume 52 has an open connection to -empty proportioning valve 53,but this is of no significance because valve 53 will close in responseto rising brake cylinder pressure before valve56 will close in responseto rising brake cylinder pressure. The brake cylinder exhaust flow in.load settingis via passage 21 past valve 16an'd through chamber 15 intothe pipe 14. Since chamber 15A is protected-by check valve .150 fromflow from chamber 1513, the brake cylinder can be exhausted intoconnection 14 only through check valve 16. When pressure in connection14 falls, valve v16 opens and brake cylinder pressure immediately startsto reduce. On cars with full load setting, volume 52 will not have beencharged, but it will have been charged to a value higher than brakecylinder pressure on cars with either of the other settings. Eachcharged volume 52 therefore discharges through the valve 58, of theproportioning valve 53, into the brake cylinder. However, the brakecylinder pressure cannot be higher than the fraction of the value ofpressure in volume 52 established by the proportioning valve, so thatwith the reduction of pressure in volume 52 will come a correspondingreduction in brake cylinder pressure until both have been depleted orreached the value held back in connection 14 by a retaining valve.

The particular advantage of the present construction arises duringrelease. A train will have some cars set for load condition, others willbe set for empty condition, and still others will be in the'intermediate setting.

To avoid the undesirable assumption of excessive and disproportionatebraking loads by the empty or lightly loaded cars, particularly duringperiods of cycling operation with retaining valves set to retainsubstantial brake cylinder pressure, it is necessary to insure promptexhaust flow from the brake cylinder after the AB valve has moved torelease position. The check valve 15C and the division of chamber 15Afrom 15B has the efiect of preventing exhaust flows from volume 52 fromdelaying exhaust flow from the brake cylinder 22.

The invention greatly improves release action as compared with thearrangement of the Ross and Safrord application, in which the exhaustflow through valves 17 and 18 effectively prevents any exhaust flowthrough valve 16 until the pressure in volume 52 has been reduced belowthat in the brake cylinder.

From the statement of operation, just given, it will be apparent thatvalve 16 functions as a one-way valve (check valve). It closes againstflow to the brake cylinder unless held open by the selector, but opensfreely at any time to permit exhaust flows. Despite the fact that valves17 and 18 are structurally identical with valve 16, they function asstop valves which when open aiford only flows toward the brake cylinderbecause the valve 15C prevents exhaust flows through each valve 17 or18.

What is claimed is:

1. In an empty and load brake the combination of a brake cylinder; abrake controlling valve device having a connection through which itcontrols pressures in the brake cylinder; and a selector valve mechanisminterposed in said connection and adapted to exercise, according toload, a limiting control on brake cylinder pressures, said selectorvalve mechanism comprising means enclosing a compensating volume; atleast one proportioning valve closing in response to brake cylinderpressure and connected to limit flow from the compensating volume to thebrake cylinder; at least one normally closed valve controllingcommunication between said connection and said volume; one-way valvemeans preventing flow through said normally closed valve toward saidconnection; a main normally closed valve controlling flow through saidconnection directly to and from said brake cylinder, said main normallyclosed valve permitting free flow from the brake cylinder at all timesand when closed device responsive to load valves selectively. t f' 2.The combination defined in claim 1 in which there aretwo proportioningvalves, each connected with the brake cylinder and characterized byclosure in response to different brake cylinder pressures, said valveshaving distinct communications with the compensating volume, one ofwhichcommunications comprises a one-way-flow valve; in which there aretwo normally closed valves in addition to the main normally closedvalve, each controllinga different communication between said connectionand said volume; and in which the selector valve device serves to openselectively said three normally closed valves.

3. The combination defined in claim 1 in which the two normally closedvalves are poppet valves each urged closed by alight biasing spring andeach closing against a discharge fiow. I

4. The combination defined in claim 2 in which the three normally closedvalves are poppet valves each urged closed by a light biasing spring andeach closing against a discharge flow.

References Cited in the file of this patent UNITED STATES PATENTS

